Microsoft has delivered yet another test build of Windows Vista Service Pack (SP) 1 to testers. On November 14, the new build — designated the SP1 Release Candiate (RC) Preview — went to a slightly expanded group of 15,000 pre-selected testers.

Microsoft made a first public beta of Vista SP1 available to 12,000 testers in September. The new build, No. 6001.17042, can be downloaded by invited testers from Microsoft’s private Connect test site. Microsoft has been making builds of Vista SP1 available to progressively larger groups of testers since earlier this spring. The company has been dangling the promise of making a test build Vista SP1 available more broadly, first as a semi-public build downloadable by Microsoft Developer Network (MSDN) members, and ultimately, by any interested parties. Microsoft posted a note to MSDN two weeks ago announcing avaiablility of a Vista SP1 beta, but later pulled the note and apologized for the false alarm.

As of November 14, Microsoft officials declined to say when broader, more public SP1 builds would hit.

Microsoft is continuing to promise delivery of Vista SP1 for the first calendar quarter of 2008. SP1 will be a rollup of fixes and updates that the company has pushed out via Windows Update since releasing Vista to manufacturing last fall. SP1 also will include support for new standards and a couple of other minor new “features.”